2022-04-20 01:28:31

by Josh Poimboeuf

Subject: [PATCH v2 01/25] objtool: Enable unreachable warnings for CLANG LTO

With IBT support in, objtool is now fully capable of following vmlinux
code flow in LTO mode. Start reporting unreachable warnings for Clang
LTO as well.

Signed-off-by: Josh Poimboeuf <[email protected]>
---
scripts/Makefile.build | 2 +-
scripts/link-vmlinux.sh | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 9717e6f6fb31..33c1ed581522 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -231,7 +231,7 @@ objtool_args = \
$(if $(part-of-module), --module) \
$(if $(CONFIG_X86_KERNEL_IBT), --lto --ibt) \
$(if $(CONFIG_FRAME_POINTER),, --no-fp) \
- $(if $(CONFIG_GCOV_KERNEL)$(CONFIG_LTO_CLANG), --no-unreachable)\
+ $(if $(CONFIG_GCOV_KERNEL), --no-unreachable) \
$(if $(CONFIG_RETPOLINE), --retpoline) \
$(if $(CONFIG_X86_SMAP), --uaccess) \
$(if $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), --mcount) \
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index 20f44504a644..9361a1ef02c9 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -140,7 +140,7 @@ objtool_link()
if ! is_enabled CONFIG_FRAME_POINTER; then
objtoolopt="${objtoolopt} --no-fp"
fi
- if is_enabled CONFIG_GCOV_KERNEL || is_enabled CONFIG_LTO_CLANG; then
+ if is_enabled CONFIG_GCOV_KERNEL; then
objtoolopt="${objtoolopt} --no-unreachable"
fi
if is_enabled CONFIG_RETPOLINE; then
--
2.34.1

2022-04-20 15:52:22

by tip-bot2 for Thomas Gleixner

Subject: [tip: x86/urgent] objtool: Enable unreachable warnings for CLANG LTO

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID: 4a5de9b76fcb3f477f73d5a63f6e27709e8af81f
Gitweb: https://git.kernel.org/tip/4a5de9b76fcb3f477f73d5a63f6e27709e8af81f
Author: Josh Poimboeuf <[email protected]>
AuthorDate: Mon, 18 Apr 2022 09:50:20 -07:00
Committer: Peter Zijlstra <[email protected]>
CommitterDate: Tue, 19 Apr 2022 21:58:48 +02:00

objtool: Enable unreachable warnings for CLANG LTO

With IBT support in, objtool is now fully capable of following vmlinux
code flow in LTO mode. Start reporting unreachable warnings for Clang
LTO as well.

Fixes: ed53a0d97192 ("x86/alternative: Use .ibt_endbr_seal to seal indirect calls")
Signed-off-by: Josh Poimboeuf <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lkml.kernel.org/r/7b12df54bceeb0761fe9fc8269ea0c00501214a9.1650300597.git.jpoimboe@redhat.com
---
scripts/Makefile.build | 2 +-
scripts/link-vmlinux.sh | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 9717e6f..33c1ed5 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -231,7 +231,7 @@ objtool_args = \
$(if $(part-of-module), --module) \
$(if $(CONFIG_X86_KERNEL_IBT), --lto --ibt) \
$(if $(CONFIG_FRAME_POINTER),, --no-fp) \
- $(if $(CONFIG_GCOV_KERNEL)$(CONFIG_LTO_CLANG), --no-unreachable)\
+ $(if $(CONFIG_GCOV_KERNEL), --no-unreachable) \
$(if $(CONFIG_RETPOLINE), --retpoline) \
$(if $(CONFIG_X86_SMAP), --uaccess) \
$(if $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), --mcount) \
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index 20f4450..9361a1e 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -140,7 +140,7 @@ objtool_link()
if ! is_enabled CONFIG_FRAME_POINTER; then
objtoolopt="${objtoolopt} --no-fp"
fi
- if is_enabled CONFIG_GCOV_KERNEL || is_enabled CONFIG_LTO_CLANG; then
+ if is_enabled CONFIG_GCOV_KERNEL; then
objtoolopt="${objtoolopt} --no-unreachable"
fi
if is_enabled CONFIG_RETPOLINE; then